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Clinical Toxicology
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Acetaminophen Poisoning: an Evidence-Based
Consensus Guideline for Out-of-Hospital Management
Richard C. Dart a; Andrew R. Erdman a; Kent R. Olson a; Gwenn Christianson a;
Anthony S. Manoguerra a; Peter A. Chyka a; E. Martin Caravati a; Paul M. Wax a;
Daniel C. Keyes a; Alan D. Woolf a; Elizabeth J. Scharman a; Lisa L. Booze a;
William G. Troutman a
a American Association of Poison Control Centers. Washington, District of Columbia.
To cite this Article: Richard C. Dart, Andrew R. Erdman, Kent R. Olson, Gwenn
Christianson, Anthony S. Manoguerra, Peter A. Chyka, E. Martin Caravati, Paul
M. Wax, Daniel C. Keyes, Alan D. Woolf, Elizabeth J. Scharman, Lisa L. Booze
and William G. Troutman , 'Acetaminophen Poisoning: an Evidence-Based
Consensus Guideline for Out-of-Hospital Management', Clinical Toxicology, 44:1, 1 - 18
To link to this article: DOI: 10.1080/15563650500394571
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Taylor and Francis 2007
Clinical Toxicology, 44:1–18, 2006Copyright Taylor & Francis LLCISSN: 0731-3810 print / 1097-9875 online DOI: 10.1080/15563650500394571
Acetaminophen Poisoning: an Evidence-Based Consensus
Guideline for Out-of-Hospital Management*
out-of-hospital management of Acetaminophen Poisoning
Richard C. Dart, M.D., Ph.D., Andrew R. Erdman, M.D., Kent R. Olson, M.D.,
Gwenn Christianson, M.S.N., Anthony S. Manoguerra, Pharm.D., Peter A.
Chyka, Pharm.D., E. Martin Caravati, M.D., M.P.H., Paul M. Wax, M.D., Daniel
C. Keyes, M.D., M.P.H., Alan D. Woolf, M.D., M.P.H., Elizabeth J. Scharman,
Pharm.D., Lisa L. Booze, Pharm.D. and William G. Troutman, Pharm.D.
American Association of Poison Control Centers, Washington, District of Columbia, USA
tus changes) should be referred to an emergency department for
The objective of this guideline is to assist poison center personnel
evaluation (Grade D). 2) Patients less than 6 years of age should be
in the appropriate out-of-hospital triage and initial management of
referred to an emergency department if the estimated acute ingestion
patients with suspected ingestions of acetaminophen. An evidence-
amount is unknown or is 200 mg/kg or more. Patients can be
based expert consensus process was used to create this guideline. This
observed at home if the dose ingested is less than 200 mg/kg (Grade
guideline applies to ingestion of acetaminophen alone and is based on
B). 3) Patients 6 years of age or older should be referred to an emer-
an assessment of current scientific and clinical information. The
gency department if they have ingested at least 10 g or 200 mg/kg
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expert consensus panel recognizes that specific patient care decisions
(whichever is lower) or when the amount ingested is unknown
may be at variance with this guideline and are the prerogative of the
(Grade D). 4) Patients referred to an emergency department should
patient and the health professionals providing care. The panel's rec-
arrive in time to have a stat serum acetaminophen concentration
ommendations follow. These recommendations are provided in chro-
determined at 4 hours after ingestion or as soon as possible thereaf-
nological order of likely clinical use. The grade of recommendation is
ter. If the time of ingestion is unknown, the patient should be referred
provided in parentheses. 1) The initial history obtained by the spe-
to an emergency department immediately (Grade D). 5) If the initial
cialist in poison information should include the patient's age and
contact with the poison center occurs more than 36 hours after the
intent (Grade B), the specific formulation and dose of acetami-
ingestion and the patient is well, the patient does not require further
nophen, the ingestion pattern (single or multiple), duration of inges-
evaluation for acetaminophen toxicity (Grade D). Repeated suprath-
tion (Grade B), and concomitant medications that might have been
erapeutic ingestion of acetaminophen (RSTI): 1) Patients under 6
ingested (Grade D). 2) Any patient with stated or suspected self-harm
years of age should be referred to an emergency department immedi-
or who is the recipient of a potentially malicious administration of
ately if they have ingested: a) 200 mg/kg or more over a single 24-
acetaminophen should be referred to an emergency department
hour period, or b) 150 mg/kg or more per 24-hour period for the pre-
immediately regardless of the amount ingested. This referral should
ceding 48 hours, or c) 100 mg/kg or more per 24-hour period for the
be guided by local poison center procedures (Grade D). 3) Activated
preceding 72 hours or longer (Grade C). 2) Patients 6 years of age or
charcoal can be considered if local poison center policies support its
older should be referred to an emergency department if they have
prehospital use, a toxic dose of acetaminophen has been taken, and
ingested: a) at least 10 g or 200 mg/kg (whichever is less) over a single
fewer than 2 hours have elapsed since the ingestion (Grade A). Gas-
24-hour period, or b) at least 6 g or 150 mg/kg (whichever is less) per
trointestinal decontamination could be particularly important if ace-
24-hour period for the preceding 48 hours or longer. In patients with
tylcysteine cannot be administered within 8 hours of ingestion. Acute,
conditions purported to increase susceptibility to acetaminophen tox-
single, unintentional ingestion of acetaminophen: 1) Any patient with
icity (alcoholism, isoniazid use, prolonged fasting), the dose of ace-
signs consistent with acetaminophen poisoning (e.g., repeated vomit-
taminophen considered as RSTI should be greater than 4 g or 100
ing, abdominal tenderness in the right upper quadrant or mental sta-
mg/kg (whichever is less) per day (Grade D). 3) Gastrointestinal
decontamination is not needed (Grade D). Other recommendations:
1) The out-of-hospital management of extended-release acetami-
nophen or multi-drug combination products containing acetami-
*Guidelines for the Management of Poisoning. Supported in full
nophen is the same as an ingestion of acetaminophen alone (Grade
by Cooperative Agreement 8 U4BHS00084 between the American
D). However, the effects of other drugs might require referral to an
Association of Poison Control Centers and the Maternal and Child
emergency department in accordance with the poison center's nor-
Health Bureau, Health Resources and Services Administration,
mal triage criteria. 2) The use of cimetidine as an antidote is not rec-
Department of Human Services. Copyright 2005 American
ommended (Grade A).
Association of Poison Control Centers.
Address correspondence to American Association of Poison
Control Centers, 3201 New Mexico Avenue NW, Suite 330,
Acetaminophen/poisoning; Poison control centers/stan-
Washington, DC 20016, USA. E-mail:
[email protected]
dards; Practice guidelines
R. C. DART ET AL.
system. When the production of NAPQI exceeds the capacity todetoxify it, as can occur in overdose, the excess NAPQI binds to
Scope of the Problem and Importance of the Guideline
cellular components and can cause the death of hepatocytes.
Ingestion of acetaminophen is a common challenge for poi-
While more than one cytochrome is capable of producing
son centers. In 2003, poison centers in the US were contacted
NAPQI, the primary source in humans is cytochrome P450
regarding ingestion of acetaminophen or an acetaminophen-
isozyme 2E1 (CYP2E1) (9,10). CYP2E1 is an inducible
containing product by 127,171 patients (1). Of these, 38,989
enzyme. Chemicals that bind to CYP2E1 may increase (induce)
were children under the age of 6 years. A total of 65,030
or decrease (inhibit) the production of NAPQI.
patients (51%) were evaluated in healthcare facilities and 327
It is well established that the time between ingestion of ace-
died. Of these, 34 (10.4%) were designated as chronic and 46
taminophen and administration of acetylcysteine affects the
(14.1%) were designated as "acute on chronic" in which a
outcome of acetaminophen poisoning. While the precise
patient already on chronic acetaminophen therapy ingested an
threshold is unknown, a delay of more than 8–10 hours results
acute overdose (1). Published data suggest that the mortality
in higher serum aminotransferase levels (11,12).
rate for patients with repeated ingestion is higher than that ofacute single ingestion of acetaminophen (2–4).
The evaluation of possible acetaminophen poisoning has
Intended Users of This Guideline
medical, economic, and social costs. In 1995, Bond and Novak
The intended users of this guideline are personnel in US
(5) estimated that 30,000–40,000 adolescents and adults ingest
poison centers. This guideline has been developed for the con-
acetaminophen each year with the intent of self-harm. They
ditions prevalent in the US. While the toxicity of acetami-
calculated that about 15,000 adolescent and adult patients are
nophen is not expected to vary in a clinically significant
hospitalized for an average of 2.7 days because of acetami-
manner in other nations, the out-of-hospital conditions could
nophen overdose. Approximately 250 of these patients die and
be much different. This guideline should not be extrapolated to
another 50 receive liver transplants. At that time, they esti-
other settings unless it has been determined that the conditions
mated that the total annual cost of intentional acetaminophen
assumed in this guideline are present.
ingestion in the US was $86.9 million. In addition, there arenumerous social and economic costs for families that arise
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Objective of This Guideline
from disruption of their lives as well as the direct costs associ-
The objective of this guideline is to assist poison center
ated with emergent visits to healthcare facilities.
personnel in the appropriate out-of-hospital triage and initial
The few data available indicate that the management of ace-
management of patients with suspected ingestions of acetami-
taminophen ingestion in the US is variable. The healthcare
nophen by 1) describing the process by which an ingestion of
facility referral threshold for acetaminophen ingestion among
acetaminophen might be managed, 2) identifying the key deci-
US poison centers ranges from 120 mg/kg to 201 mg/kg of ace-
sion elements, 3) providing clear and practical recommenda-
taminophen (6). A guideline that effectively determines the
tions that reflect the current state of knowledge, and 4)
need for referral could optimize patient outcome, reduce costs,
identifying needs for research. This guideline applies to inges-
and reduce disruption for patients and caregivers.
tion of acetaminophen alone. Co-ingestion of additional sub-stances could require different referral and management
recommendations, depending on the combined toxicities of thesubstances.
This guideline is based on an assessment of current scien-
The term out-of-hospital is defined as the period before a
tific and clinical information. The expert consensus panel rec-
patient reaches a healthcare facility. An acute ingestion is
ognizes that specific patient care decisions may be at variance
defined as any number of ingestions that occur within a period
with this guideline and are the prerogative of the patient and
of up to 8 hours. In recent years, the phenomenon of "chronic"
health professionals providing care, considering all of the cir-
acetaminophen toxicity has been described (7,8). Repeated
cumstances involved. This guideline does not substitute for
supratherapeutic ingestion (RSTI) involves any pattern of mul-
clinical judgment.
tiple ingestions over a period of greater than 24 hours thatresults in a total dosage of more than 4 g per day.
Pathophysiology of Acetaminophen Toxicity
The methodology used for the preparation of this guideline
Acetaminophen is rapidly and completely absorbed after oral
was developed after reviewing the list of key elements of
administration. It exhibits a large first-pass effect with uptake
guidelines described by Shaneyfelt et al. (13). An expert con-
and metabolism in the liver. The toxicity of acetaminophen is
sensus panel was established to oversee the guideline develop-
related to the production of the reactive intermediate N-acetyl-p-
ment process (Appendix 1). The American Association of
benzoquinonimine (NAPQI) by the hepatic cytochrome P450
Poison Control Centers (AAPCC), the American Academy of
OUT-OF-HOSPITAL MANAGEMENT OF ACETAMINOPHEN POISONING
Clinical Toxicology (AACT), and the American College of
Medical Toxicology (ACMT) appointed members of their
All articles that were retrieved from the search were
organizations to serve as panel members. To serve on the
reviewed by a single abstractor. Each article was assigned a
expert consensus panel, an individual had to have an excep-
level of evidence score from 1 to 6 using the rating scheme
tional record of accomplishment in clinical care and scientific
developed by the Centre for Evidence-Based Medicine at
research in toxicology, board certification as a clinical or med-
Oxford University (Appendix 2); the complete paper was then
ical toxicologist, significant US poison center experience, and
reviewed for original human data regarding the toxic effects of
be an opinion leader with broad esteem. Two Specialists in
acetaminophen or original human data directly relevant to the
Poison Information were included as full panel members to
out-of-hospital management of patients with acetaminophen
provide the viewpoint of the end-users of the guideline.
overdose. Articles without original human data were not evalu-ated. Doses of acetaminophen, resultant effects, times of onset
of effects, therapeutic interventions or decontamination mea-sures given, efficacy or results of any interventions, and overall
The National Library of Medicine's MEDLINE database
patient outcomes were compiled into a table and a brief sum-
was searched (1966 to January 2003) using acetaminophen as a
mary description of each article was written. The completed
MeSH term with the subheadings poisoning (po) or toxicity
table of all abstracted articles was then forwarded to the guide-
(to), limited to humans. MEDLINE and PreMEDLINE (1966–
line primary author and panel members for review and consid-
January 2003) were searched using acetaminophen or paraceta-
eration in developing the guideline. This full evidence table is
mol as textwords (title, abstract, MeSH term, CAS registry)
plus either poison* or overdos*, limited to humans. This same
20tables/apap%20evidence%20table.pdf. Every attempt was
process was repeated in International Pharmaceutical Abstracts
made to locate significant foreign language articles and have
(1970–January 2003, excluding abstracts of meeting presenta-
their crucial information extracted, translated, and tabulated. In
tions), Science Citation Index (1977–January 2003), Database
addition to the evidence table, several brief sub-tables were
of Abstracts of Reviews of Effects (accessed January 2003),
generated that included all of the articles and data relating to a
Cochrane Database of Systematic Reviews (accessed January
particular topic (e.g., dose of acetaminophen in acute pediatric
2003), and Cochrane Central Register of Controlled Trials
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ingestions reported to cause toxicity). These were also for-
(accessed January 2003). A similar search was conducted in
warded to the primary author and guideline panel members.
EMBASE using both acetaminophen and paracetamol as pri-
Finally, a written summary of the data was created and distrib-
mary search terms. Index Medicus was hand-searched (1960–
uted by the abstractor. Copies of all of the articles were made
1965) using the term "analgesics and antipyretics" through
available for reading by the panel members on a secure
1964 and "acetaminophen" for 1965. Reactions (1980–January
AAPCC website.
2003), the acetaminophen poisoning management in POISIN-DEX (14), the Cochrane systematic review of interventions foracetaminophen overdoses (15), and the chapter bibliographies
Guideline Writing and Review
in four major toxicology textbooks (17–19) were reviewed for
A guideline draft was prepared by the primary author. The
citations of additional articles with original human data. The
draft was submitted to the expert consensus panel for com-
bibliographies of recovered articles were reviewed to identify
ment. Using a modified Delphi process, comments from the
previously undiscovered articles.
expert consensus panel members were collected, copied intoa table of comments, and submitted to the primary author forresponse. The primary author responded to each comment in
the table and, when appropriate, the guideline draft was mod-
The recovered citations were entered into an EndNote
ified to incorporate changes suggested by the panel. The
library and duplicate entries were eliminated. The abstracts of
revised guideline draft was again reviewed by the panel and,
these articles were reviewed, looking specifically for those that
if there was no strong objection by any panelist to any of the
dealt with 1) estimations of mg/kg or ingested doses with or
changes made by the primary author, the draft was prepared
without subsequent signs or symptoms, and 2) management
for the external review process. External review of the second
techniques that might be suitable for out-of-hospital use (e.g.,
draft was conducted by distributing it electronically to
gastrointestinal decontamination). The panel agreed that ace-
AAPCC, AACT, and ACMT members and the secondary
tylcysteine therapy could be considered for initiation in the
review panel. The secondary review panel consisted of repre-
prehospital setting. Articles excluded were those that did not
sentatives from the federal government, public health, emer-
meet either of the preceding criteria, did not add new data (e.g.,
gency services, pediatrics, pharmacy practice, and consumer
some reviews and editorials), described inpatient-only proce-
organizations (Appendix 3). Comments were submitted via a
dures (e.g., dialysis), or described treatments that were unlikely
discussion thread on the AAPCC website or privately through
to be used (e.g., methionine).
e-mail communication to AAPCC staff. All submitted
R. C. DART ET AL.
comments were stripped of any information that would iden-
acetaminophen metabolite may be disproportionately greater in
tify their sources, copied into a table of comments, and
small children; therefore, the capacity of a young child to
reviewed by the expert consensus panel and the primary
metabolize acetaminophen in a nontoxic manner may be
author. The primary author responded to each comment in the
greater than that of an adult.
table and his responses and subsequent changes in the guide-line were reviewed and accepted by the panel. Following ameeting of the expert consensus panel, the final revision of
Dose and Pattern of Acetaminophen Ingestion
the guideline was prepared.
The evidence regarding the relationship between acetami-
nophen dose and toxicity is limited primarily to case reportsand case series (level 4) and to cohort or case-control studies
KEY DECISION ELEMENTS
(levels 2 and 3, respectively). Studies reviewed for this guide-
The panel identified patient age and intent as well as the
line were categorized by age (less than 6 years of age or 6 years
estimated dose and timing of ingestion as critical elements
of age and older) and by pattern (acute ingestion, repeated
needed to evaluate an ingestion of acetaminophen. This pro-
ingestion). In most cases, toxicity actually meant the potential
cess has not been experimentally evaluated in published stud-
for toxicity as predicted by the Rumack-Matthew nomogram.
ies. However, there are well-known practice patterns ascribed
In some articles, information on pediatric overdoses was com-
to by essentially all US poison centers. For example, all poison
mingled with information on adult overdoses, making informa-
centers obtain a defined information data set from each caller.
tion on the two groups impossible to separate. Furthermore,
The standard poison center process includes ascertainment of
some articles defined pediatric patients as less than 17 years of
the history, assessment of this historical information in the
age while others defined them as less than 7 or 12 years of age.
context of the patient's exposure, estimation of the dose
A survey of US poison center managers found that the dose
ingested, and recommendation for referral and initial out-of-
threshold triggering referral to a healthcare facility varied
greatly. Triage threshold values ranged from 120 to 201 mg/kgfor acute, unintentional ingestions of acetaminophen. Centersusing relatively low thresholds (e.g., 150 mg/kg) referredpatients to hospitals more frequently than centers using higher
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REVIEW OF THE MEDICAL LITERATURE
thresholds (e.g., 200 mg/kg) (6).
Patient Age and Intent
A potentially toxic ingestion of acetaminophen may occur
Acute Single Ingestions by Patients 6 Years of Age and Older
in an adult or a child. There are fundamental differences
No randomized clinical trials involving the out-of-hospital
between patients below the age of 6 years and patients who are
treatment of intentional acetaminophen overdose have been
6 years of age or older. Young patients are often discovered
reported. Several randomized controlled trials (level 1b) have
during or soon after ingestion. Older patients are more likely to
reported the administration of an acute single supratherapeutic
attempt self-harm and to conceal the attempt. Most deaths from
dose of acetaminophen. Doses in these studies have ranged
acetaminophen poisoning occur in adults with acute overdoses.
from 4 to 7.8 g (up to 75–80 mg/kg). Serum aminotransferase
In contrast, nearly all deaths attributed to acetaminophen
levels were not reported in these studies, but all of the patients
reported in the medical literature regarding children under the
survived and none was noted to develop clinical signs of
age of 6 years have involved RSTI overdosage. There were no
hepatotoxicity (25–30). The applicability of these studies to
articles identified that directly addressed the relationship
acetaminophen overdose is limited by the small number of
between patient age and intent (i.e., unintentional vs. inten-
subjects, the use of healthy subjects, and the lack of laboratory
tional ingestion). The Toxic Exposure Surveillance System of
investigations to assess subclinical hepatic toxicity.
the American Association of Poison Control Centers lists 14
Only observational studies were found relating the esti-
deaths in children under the age of 6 years in the period 1990–
mated dose of acetaminophen to liver injury or potential toxic-
2003. One of these deaths involved an acute exposure to ace-
ity as represented by the Rumack-Matthew nomogram. A
taminophen but the child had also ingested diphenhydramine
number of case reports and case series (level 4), and various
and iron (20).
cohort or case-control studies (levels 2b and 3b) containing
Published evidence suggests that preschool children are less
specific information on ingested doses and patient outcome
susceptible to the same weight-adjusted doses and serum con-
have reported acetaminophen levels above the possible toxicity
centrations of acetaminophen that are associated with severe
line (31–33). The smallest reported doses associated with
toxicity in older patients (21,22). This may be due to an
evidence of hepatic injury have ranged from 3.25 to 10 g
increased capacity to metabolize acetaminophen through non-
(2,34–46). A cohort analysis (level 2b) described several
toxic mechanisms (23). Furthermore, the liver size of a small
patients in whom acute doses of less than 12 g were associated
child is larger in proportion to body weight than that of an adult
with hepatotoxicity, but the exact doses were not specified
(24). The amount of glutathione available to detoxify the
(47). This same study reported deaths in patients with reported
OUT-OF-HOSPITAL MANAGEMENT OF ACETAMINOPHEN POISONING
doses as low as 15 g. In contrast, some reports have described
aminotransferase levels (40,64–66). Case reports (level 4), case
large single ingestions with documented serum concentrations
series (level 4), and cohort (level 2b) or case-control (level 3b)
of acetaminophen above the possible or probable toxicity
studies have reported either greater severity of injury or a
nomogram lines that did not result in toxicity (48).
lower threshold dose for the development of hepatotoxicity
The conflicting reports of hepatic injury following doses at
after acetaminophen ingestion by patients chronically ingesting
or just above the therapeutic dose are likely explained by the
alcohol or other compounds thought to increase susceptibility
nature of the evidence. Studies (levels 2b and 4) have docu-
to acetaminophen toxicity (e.g., isoniazid use, prolonged fast-
mented that there is poor correlation between the reported
ing) (2,34,36–38,40,41,46,50,65,67–72). Evidence (level 4)
dose and either subsequent acetaminophen serum concentra-
indicating that a patient's alcoholic state does not contribute to
tion or clinical outcome (31,42,43,49–53). The correlation
outcome has also been reported (12,42).
between reported dose and subsequent serum concentration
Each of these reports uses the theoretical framework of
or toxicity for children with unintentional ingestion is also
enhanced production of NAPQI and the reduction of defenses
poor (53–55).
as represented by glutathione. Chronic ethanol abuse is a use-
The history of ingestion might be inaccurate because it is
ful condition to study because of its prevalence and because it
often obtained during a period of extreme emotional stress for
involves both increased production of NAPQI and reduction of
both the patient and their family. Furthermore, there are often
glutathione (73). The primary inducers of CYP2E1 with medi-
confounding factors such as co-ingestion of ethanol or other
cal relevance are ethanol, acetone, and isoniazid. It is important
drugs that affect the central nervous system. In most reports
to understand that drugs that induce CYP2E1 must bind to the
available, the accuracy of the history was not addressed and the
enzyme and thereby are competitive inhibitors of the enzyme.
history was not confirmed by outside sources (e.g., family
Thus, when both ethanol and acetaminophen are ingested con-
members) or objective evidence (e.g., empty product contain-
currently, the metabolism by CYP2E1 and hepatotoxicity of
ers). Fortunately, accurate dose information is usually not
acetaminophen are decreased (10). When ethanol is subse-
needed for patients 6 years of age or older because treatment is
quently eliminated, however, the induced enzyme remains and
guided by the serum acetaminophen concentration.
metabolism of acetaminophen is increased for several hours(10). Therefore, concurrent ingestion of acetaminophen and
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Repeated Supratherapeutic Ingestion (RSTI) by Patients 6
ethanol is not expected to enhance injury from acetaminophen.
Years of Age and Older
However, acetaminophen ingestion (especially in overdose)
The maximum daily dosage of acetaminophen recom-
soon after elimination of ethanol can theoretically potentiate
mended by a major manufacturer is 1 g every 4 hours, not to
the effect of acetaminophen overdosage.
exceed 4 g a day for patients 12 years of age or older (56). Four
While animal and human data support the concept that
randomized clinical trials (level 1b) were found that involved
induction of CYP2E1 occurs during the use of ethanol, the
multiple ingestions of acetaminophen over a period of more
clinical meaning of this effect remains unclear. For example,
than 1 day. Gelotte et al. (57) administered 4, 6, or 8 g/day in
level 1b data indicate that the effect of ethanol is not clinically
divided doses to adults for 3 days. These doses were not
apparent at a therapeutic acetaminophen dosage. The adminis-
associated with accumulation of acetaminophen, changes in
tration of acetaminophen 4 g/day for 2 days to confirmed alco-
serum aminotransferase levels, or effects on other monitoring
holic patients under controlled conditions did not produce
parameters. The application of this study in clinical practice is
increases in serum aminotransferase levels or alterations of
limited by its use of normal subjects and the controlled envi-
international normalized ratios (74). Similarly, the administra-
ronment of a clinical research center. Other prospective studies
tion of the maximum dosage to patients with liver disease
administered 4–6 g/day to patients without adverse clinical
(hepatitis, cirrhosis) was also found to not affect serum ami-
effect, including patients with acute stroke and head and neck
notransferase levels (75).
cancer (58–61). Level 4 reports describe ingestion of over
A systematic review (level 1a) of publications involving
20 g/day for years (62) and ingestion of 25 g over 25 hours
alcohol and acetaminophen has documented a contrast between
(63) without adverse effects.
prospective studies and case reports. All prospective articles
The interpretation of the medical literature of repeated ace-
failed to find liver injury at therapeutic doses. In contrast,
taminophen doses is complicated by the effects of conditions
many case reports and small case series found an association of
that are thought to lower the threshold for toxicity. These are
liver injury in alcoholic patients with dosages of 4 g/day or less
generally categorized as either conditions that increase the
(76). There are no data that address the issue of CYP2E1 on
production of the reactive metabolite NAPQI or that decrease
RSTI acetaminophen. If alcohol or other disease states enhance
the ability to detoxify NAPQI (e.g., decreased concentration
the toxicity of acetaminophen, the dosage at which the phe-
of glutathione). Authors report that low daily doses of acetami-
nomenon develops is unknown.
nophen, ranging from minimal daily doses of 2.4–6 g in
Patients with acute co-ingestion of acetaminophen with alco-
alcoholics, patients with starvation, or those on chronic antitu-
hol or gastrointestinal antimotility agents and patients taking
berculous medications have been associated with elevated
cimetidine chronically have been reported to be at decreased
R. C. DART ET AL.
risk of liver injury (levels 2b and 4) (31,47,50,53,77,78). Other
2.5 g of acetaminophen (84). A 14-year-old girl developed an
authors have found no correlation between acute alcohol
INR of 1.6 after an acute ingestion of 4 g acetaminophen; how-
consumption and severity of toxicity (level 2b) (46). Schmidt
ever, she had also received an excessive dose of acetylcysteine
et al. (47) reported that acute ingestion of benzodiazepines
(40 g) intravenously prior to the measurement (85). As for
exacerbated hepatic encephalopathy after acute acetaminophen
adults, the few cases of toxicity associated with low doses
overdose but that acute use of opiates was protective against
stand in contrast to the numerous cases in which toxicity was
hepatotoxicity (level 2b). Schmidt et al. also reported that
not observed until acute doses exceed 150 mg/kg/day (48). The
chronic use of opioids, benzodiazepines, and acetaminophen
most likely explanation is historical inaccuracy as described
increased the risks of various negative outcomes after acute
above under adult overdose.
acetaminophen overdoses. The meaning of the conflictingresults of these studies is unclear. It is likely that most differ-ences reported are the result of an unrecognized confounder or
Repeated Supratherapeutic Ingestion (RSTI) by Patients Less
systematic error. For example, the history of RSTI is typically
than 6 Years of Age
taken after days of ingestion. Often the period of ingestion
No randomized clinical trials could be found that evaluated
has included events known to impair memory such alcohol
the minimum cumulative daily dose for the development of
intoxication or co-ingestion of psychoactive drugs as well as
laboratory evidence of liver injury after pediatric RSTI (69,
difficulties imposed by an underlying illness (fever, sleep depri-
86–90). The dosages of acetaminophen associated with eleva-
vation, etc.). While these results may stimulate future studies,
tion of aminotransferase levels in case reports (level 4), case
they are too uncertain to apply to a clinical guideline.
series (level 4), and cohort analyses (level 2b) have rangedfrom the normal therapeutic dosage (20 mg/kg/day) to 600 mg/
Acute Single Ingestions by Patients Less than 6 Years of Age
kg/day or more (90). Most reports indicate that dosages of 120
No randomized clinical trials were found evaluating the
to 174 mg/kg/day for multiple days are needed to produce tox-
acute threshold dose for the development of clinical acetami-
icity (69,82,87).
nophen toxicity (i.e., laboratory evidence of liver injury) or
Two case series (level 4) reported toxicity associated with
even potential toxicity as determined by the Rumack-Matthew
histories of smaller ingestions. One report identified 47 children
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nomogram in children of any age. Several observational studies
below the age of 12 years with hepatotoxicity after acetami-
investigated the potential safety and efficacy of various poison
nophen RSTI. Toxicity developed after reported daily doses of
center protocols in the management of acute, accidental pediat-
60–420 mg/kg/day for 1–21 days (89). A retrospective review of
ric (less than 6 or 7 years of age) ingestions of acetaminophen
a liver transplant service identified four children who developed
(6,55,68,79,80). Most articles (levels 2b, 3b, and 4) suggest that
severe hepatic injury after doses of 20–71 mg/kg/day for 7 days
patients with ingestions of less than 200 mg/kg could be man-
(90). Another case series recorded doses ranging from 23 to 100
aged at home, provided that the acetaminophen dose is known.
mg/kg day associated with liver injury in children (91). Perhaps
One level 4 study created a model to predict serum concentra-
due to inaccurate histories provided by patients, the data pre-
tions after ingestion of acetaminophen (81). The authors con-
sented contain many inconsistencies. For example, the highest
cluded that a referral dose of 250 mg/kg was appropriate for
serum acetaminophen concentration reported among children
children. This study did not include any children with serum
with presumed acetaminophen toxicity was 14 mg/L after dos-
acetaminophen concentrations above the "probable toxicity"
ages ranging from 20 to 200 mg/kg/day.
line of the Rumack-Matthew nomogram. However, it is likely
In contrast, prospective and retrospective studies in children
that all of these studies had insufficient power to detect the rare
have used acetaminophen dosages up to and exceeding 90 mg/
event of toxicity after a single dose of acetaminophen in a child
kg/day without liver injury. Lesko and Mitchell (92) found no
under the age of 6 years. Very few cases of toxicity after acute
clinical evidence of toxicity in a prospective study of 28,130
single ingestion by a child under the age of 6 years were found
children administered up to 60 mg/kg/day (level 1b). Further,
in the medical literature and in the AAPCC TESS database (20).
both level 1b and level 4 studies have documented the use of
If this type of toxicity occurs, it is rare.
dosage above 90 mg/kg/day without adverse effect (93–96).
In contrast, case reports and case series (level 4) and various
Thus, the data for pediatric RSTI are conflicting and with a pat-
cohort (level 2b) or case-control studies (level 3b) containing
tern similar to reports involving acute overdose—prospectively
information on specific ingested doses and patient outcome
collected data are sparse and do not indicate potential for hepatic
have reported potential toxicity or actual toxicity in children
injury, while retrospectively collected data provide evidence of
less than 6 years old with single doses thought to be in the
an association of relatively low dosages, even therapeutic dos-
range of 146 to 190 mg/kg (82,83).
ages, with liver injury. Again, the cause is likely to be historical
Acute single ingestion resulting in toxicity has been
inaccuracies. Overdoses in children are subject to the same con-
reported more commonly in adolescents. The lowest dose
cerns as in adults but also present their own unique set of con-
resulting in liver injury involved a 13-year-old of unknown
cerns as parents may over- or underestimate the actual ingested
weight who died of hepatic failure after reportedly ingesting
dose depending on the circumstances.
OUT-OF-HOSPITAL MANAGEMENT OF ACETAMINOPHEN POISONING
Potential Out-of-Hospital Management Techniques to
charcoal, lavage, or untreated control). However, the primary out-
Prevent or Ameliorate Acetaminophen Toxicity After
come measure was percent reduction of the serial serum acetami-
nophen concentration (first concentration compared with last),
The consensus panel identified these potential strategies
which might not be an adequate outcome indicator (97). The
for reducing acetaminophen absorption in the out-of-hospital
study found that the three decontamination methods reduced
setting: 1) reducing absorption, 2) inhibiting metabolism, or 3)
acetaminophen serum concentrations by 39–51%.
detoxifying the reactive intermediate metabolite, NAPQI.
Two randomized controlled trials (level 1b) were identified
Absorption can be decreased by gastrointestinal decontamina-
that examined the efficacy of ipecac-induced emesis in simu-
tion, metabolism can be inhibited by drugs such as cimetidine,
lated overdose. In one study, ipecac syrup given within 5 min-
and detoxification can be accomplished by the administration of
utes of ingestion was effective at reducing overall
acetylcysteine. The risk-benefit analysis of these techniques is
acetaminophen absorption by 66%, as measured by the area
difficult. The primary difficulty is that the treatment of acetami-
under the curve (AUC) but was not effective when adminis-
nophen toxicity with acetylcysteine is usually successful when
tered at 30 or 60 minutes after ingestion (98). In the second
acetylcysteine is initiated within 8–10 hours of acute ingestion
study, ipecac syrup given 1 hour after simulated overdose was
(11,12). Thus, it is difficult to show an improvement in patient
effective at reducing the acetaminophen AUC compared with
outcome for any out-of-hospital intervention because the admin-
control by about 25% and its efficacy was comparable to acti-
istration of acetylcysteine reduces the potential benefit of the
vated charcoal (99).
intervention to near zero. However, potential benefit could be
Several cohort analyses (level 2b) based on retrospective
realized in situations where acetylcysteine is not available.
reviews evaluated the efficacy of ipecac syrup after acetami-
There were data available in the literature for each type of
nophen overdose. One found a decrease in the likelihood of
intervention; however, there were no studies found that specif-
developing severe hepatotoxicity or death in the cohort of
ically addressed the out-of-hospital administration of various
patients who had emesis or gastric lavage within 6 hours of
antidotes or treatments.
ingestion (100). The two other studies focused on children.
One found that ipecac-induced emesis within 60 minutesreduced the mean 4-hour serum acetaminophen concentration
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by 77% based on a comparison with 4-hour concentrations pre-
The potential strategies for reducing absorption after ace-
dicted by a pharmacokinetic model. After 60 minutes, the
taminophen ingestion that could be reasonably be performed in
mean reduction of the 4-hour concentration was about 40%
an out-of-hospital setting include emesis with ipecac syrup or
(101). The second pediatric cohort investigation found that
administration of activated charcoal. Only those articles that
4-hour acetaminophen concentrations were reduced by about
contained specific information about these measures as well as
50%, compared with untreated controls when emesis occurred
some description of their outcomes have been included.
within 90 minutes of the ingestion (79).
All reports in the medical literature combined out-of-hospi-
One case-control study (level 3b) of patients with acute ace-
tal and in-hospital interventions in the setting of acute inges-
taminophen overdose found that the group that developed
tion. There were no articles specifically investigating the out-
hepatic injury was less likely to have undergone gastric empty-
of-hospital use of induced emesis or activated charcoal. There
ing by lavage or induced emesis than the group that did not
were also no articles addressing the effectiveness of decontam-
develop hepatic injury; however, the difference was not statis-
ination measures for an RSTI pattern of ingestion. Since stud-
tically significant (33).
ies of RSTI demonstrate that liver injury develops after more
Six randomized controlled trials (level 1b) have investi-
than 1 day of ingestion, these patients probably present for care
gated the efficacy of activated charcoal in reducing acetami-
too late for decontamination to be effective.
nophen absorption in healthy volunteers receiving
Two level-1 articles examined decontamination measures
supratherapeutic, but nontoxic, doses of acetaminophen. In
after acute overdose. The remaining decontamination data are
these studies, activated charcoal (50–60 g) reduced the serum
limited to randomized controlled trials (level 1b) of simulated
acetaminophen AUC by 25–67% if given at 1 hour after inges-
overdose in healthy volunteers given a single subtoxic, but
tion (102–105). Another study found that activated charcoal
supratherapeutic, dose of acetaminophen, and observational
(1 g/kg) mixed with soda and given 15 minutes after simulated
studies such as cohort (level 2b) or case-control (level 3b) anal-
overdose reduced acetaminophen absorption by 74% (30). The
yses of patients who had ingested single overdoses.
efficacy of activated charcoal decreased when it was adminis-
A systematic review (level 1a) concluded that activated char-
tered more than 1 hour after ingestion in most studies and one
coal, gastric lavage, and ipecac-induced emesis are able to reduce
study found no benefit in AUC or 4-hour serum concentration
the absorption of acetaminophen, but also concluded that their
when activated charcoal was given 2–4 hours after simulated
clinical benefit is unclear (15). One randomized controlled trial
overdose (29,103). One study reported a reduction in AUC of
(level 1b) of overdose patients examined the efficacy of different
23% compared with control when activated charcoal was given
decontamination procedures (ipecac-induced emesis, activated
2 hours after ingestion (104).
R. C. DART ET AL.
Two nonrandomized but controlled studies (level 2b) using
less with left lateral decubitus and supine positions compared
simulated overdose were identified. One found a decrease in
to prone, sitting, or right lateral decubitus (26).
AUC (about 60%) with immediate administration of activatedcharcoal, but the difference was smaller and not statistically
Limitations of Published Decontamination Data
significant when activated charcoal was given at 1 hour after
Simulated overdose studies in volunteers might be a poor
ingestion (106). The other study found an AUC reduction of
representation of what occurs in real acetaminophen overdoses,
about 50% with both immediate and 30-minute activated char-
in which larger doses are ingested, patients are not fasting, and
coal administration (107).
co-ingestants that affect gastrointestinal motility might be
One prospective cohort (level 2b) study of activated char-
involved. Volunteer studies might underestimate the efficacy
coal in adult acetaminophen overdoses found that patients who
of decontamination if gastric emptying is delayed in overdoses
received activated charcoal plus acetylcysteine within 8 hours
or they might overestimate efficacy if the decontamination
of their overdoses were significantly less likely to develop liver
measures become less effective with massive acetaminophen
injury or hepatotoxicity when compared with those receiving
doses (by stoichiometry), tablet bezoar formation, or because
acetylcysteine alone within 8 hours (108). Another cohort
of activated charcoal binding to food or other co-ingestants
study (level 2b) in overdose patients found that the group that
rather than acetaminophen.
received activated charcoal within 2 hours had fewer patients
There are also challenges in the interpretation of cohort and
who subsequently developed 4-hour serum acetaminophen
case-control studies. There could be other differences between
concentrations in the possible or probable toxicity range com-
the cases and controls other than the variable being tested (e.g.,
pared with the group that did not receive activated charcoal.
ingested doses, times to treatment might differ, and use of ace-
The benefit decreased after 2 hours (109).
tylcysteine might differ). They also tend to rely on retrospec-
Two studies directly compared ipecac-induced emesis to
tive data-gathering, a process that produces its own unique
activated charcoal. One randomized controlled (level 1b) study
disadvantages (e.g., decisions on treatment could have been
in simulated overdose patients found no difference between the
based on some piece of history that was not recorded or
two in efficacy as measured by reduction in AUC (99). A ran-
recorded inaccurately in the medical record).
domized trial (level 1b) in simulated overdose patients found a
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slightly more rapid decline in acetaminophen serum concentra-
Inhibition of Acetaminophen Metabolism
tions with activated charcoal compared to ipecac-induced eme-
Cimetidine has been proposed as an antidote for acetami-
sis (97). Another level-1b study looked at the difference
nophen poisoning (78,114–116). It has the advantage of being
between activated charcoal with sorbitol and activated charcoal
available as an over-the-counter (OTC) medication. One pro-
without sorbitol but found no significant difference in efficacy
spective (level 1b) trial in overdose patients presenting more
as measured by AUC (102).
than 8 hours after ingestion found no added benefit (as mea-
Two studies found activated charcoal to be ineffective in
sured by liver function tests) from cimetidine when it was
reducing acetaminophen absorption. One was a simulated
added to acetylcysteine treatment (116). One nonrandomized,
overdose trial in volunteers (level 2b) that found no difference
controlled trial in healthy adults with simulated overdoses
in AUC between controls and those receiving 25 g of acti-
found that cimetidine, given orally for 2 days prior to acetami-
vated charcoal 15 minutes after ingestion (110). A retrospec-
nophen, decreased the overall clearance of acetaminophen,
tive cohort (level 2b) study in children with actual overdoses
implying some benefit to its administration in overdoses (78).
found no difference in 4-hour serum acetaminophen concen-
Three case reports (level 4) of its use had inconclusive out-
trations between the activated charcoal and no decontamina-
comes (70,115,117).
tion cohorts (54).
Two articles (level 2b and level 4) reported on the use of
general gastric decontamination measures but did not specify
Detoxification of Acetaminophen Metabolite (NAPQI)
the specific method investigated (51,55).
The pharmaceutical formulation of acetylcysteine (but not
Studies indicate that the use of decontamination measures
the OTC tablet formulation) has been tested and found to
have the potential to interfere with the effectiveness of acetyl-
reduce or prevent liver injury following acetaminophen inges-
cysteine. For example, ipecac syrup induces vomiting that can
tion (17,118). There were no randomized controlled (level 1b)
interfere with the administration of oral acetylcysteine. Acti-
trials evaluating the efficacy of acetylcysteine in the out-of-
vated charcoal binds acetylcysteine (111) and reduces its bio-
hospital setting. Many observational studies reported the use of
availability (112), although the clinical importance of these
acetylcysteine in the out-of-hospital setting but did not explic-
findings is unknown (113).
itly give information on its effectiveness and so they are notspecifically addressed here (3,44,51,53,54,67,72,119,120). In
Body Position
addition, multiple case reports and case series (level 4) were
One randomized, controlled trial (level 1b) of simulated
reported in which the efficacy of acetylcysteine could not be
overdose found that the acetaminophen AUC was significantly
OUT-OF-HOSPITAL MANAGEMENT OF ACETAMINOPHEN POISONING
Retrospective cohort (level 2b), prospective cohort (level
the loss of efficacy as time to administration increases indicate
2b), and case-control (level 3b) analyses have reported that
that acetylcysteine is effective.
acetylcysteine, either in its usual oral or intravenous dosage, oras an unspecified dosage or route of administration, is effective
Role of Different Acetaminophen Formulations
at reducing mortality or at reducing the subsequent incidence
Acetaminophen is available in extended-release formula-
and severity of liver injury after acetaminophen overdose
tions that contain more acetaminophen (650 mg/tablet), are
released over a longer period than the usual "extra strength"
The degree of acetylcysteine efficacy also appears to
formulations, and are intended for use three times per day.
depend on the time after overdose at which it is given. Read et
Case reports and case series (level 4) indicate that a patient's
al. (50) found that patients with serum acetaminophen concen-
serum acetaminophen concentration might cross the Rumack-
trations above the treatment line receiving acetylcysteine
Matthew nomogram lines at times much later than anticipated.
within 16 hours (dose and route not specified) had a survival
Six articles addressing extended-release acetaminophen
rate of 94% (18 of 19) compared to 0% (none of seven) in an
overdose were identified (27,28,125–128). Two studies were
untreated cohort (level 2b). Prescott et al. reported that intrave-
randomized, controlled (level 1b) pharmacokinetic compari-
nous infusion of acetylcysteine more than 10 hours after ace-
sons with regular extra-strength acetaminophen in healthy vol-
taminophen ingestion in 15 patients was associated with more
unteers taking simulated overdoses. In one study, both the peak
severe liver damage than was associated with earlier adminis-
serum acetaminophen concentration and the AUC were signifi-
tration (level 4) (16,122). Smilkstein et al. (17) found that the
cantly lower for extended-release formulation compared with
72-hour oral acetylcysteine regimen was most effective if
similar doses of the extra-strength formulation. Time-to-peak
given within 8 hours of ingestion. It was still effective, albeit
concentration was not significantly longer (27). In the second
less so, if administered up to 24 hours after ingestion (level 4).
study, peak acetaminophen concentrations were significantly
Bray et al. (123) reported that survival in a cohort treated with
lower for the extended-release product, but AUC and time to
acetylcysteine within 24 hours of ingestion was 65% vs. 38%
peak were not different from the typical extra-strength product
for an untreated cohort (level 2b). In another level-2b study,
Bray et al. (38) noted that survival was 67% in patients treated
The other articles were case reports or case series (level 4)
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within 8–12 hours compared to 7% in untreated controls. In a
of overdoses with extended-release acetaminophen in which
level-2b study, Makin et al. (42) showed that survival was bet-
several patients were noted to have serum acetaminophen con-
ter in patients treated with intravenous acetylcysteine within 24
centrations that crossed the nomogram line despite initially
hours (80%) and that patients treated after 24 hours were still
nontoxic serum concentrations (126–128). Hepatotoxicity
more likely (78%) to survive than untreated controls (48%).
developed in one patient who ingested a handful of extended-
Other studies have supported the concept that an increase in
release acetaminophen and did not present to an emergency
the interval between acetaminophen ingestion and acetylcys-
department until 19 hours after the ingestion where she was
teine administration is associated with a higher rate of liver
treated with acetylcysteine (125).
injury (2,33,46,52,82,83,121). In a large cohort analysis (level
Acetaminophen is also available in a formulation containing
2b), Schmidt et al. (47) found that mortality after acute ace-
diphenhydramine. In overdose, diphenhydramine could theoreti-
taminophen overdose depended on time to acetylcysteine treat-
cally decrease gastrointestinal motility and slow absorption of
ment, with mortality rates for the 0–12, 12–24, 24–48, and
acetaminophen. One case report (level 4) described a patient
more than 48 hour groups of 0.4%, 6%, 13%, and 19%, respec-
who had acutely ingested 46 g of acetaminophen plus 2.3 g
tively. One study (level 2b) found no difference in survival
diphenhydramine and developed a serum acetaminophen con-
between small treated and untreated cohorts (43).
centration that crossed the nomogram line for possible toxicity at
Few studies have examined the efficacy of acetylcysteine in
10.5 hours despite earlier measurements that were below the line
patients with RSTI. Makin et al. (42) included 45 patients with
(129). The patient developed mild liver function abnormalities.
RSTI; however, the study did not specifically address the effi-
Although unusual, some exposures to acetaminophen occur
cacy of acetylcysteine in this subgroup (level 2b). Several case
by rectal suppositories. The panel concluded that the out-of-
reports (level 4) of its use in patients with RSTI were located,
hospital management of patients with rectal exposure should
but no assessment of benefit from acetylcysteine could be
be assessed in the same manner as those who have ingested
gleaned from them (63,64,86–88,124). No studies were found
that directly compared different routes or dosages of acetylcys-teine. Spiller et al. (108) found that activated charcoal did notinterfere with acetylcysteine efficacy as measured by liver
Poison Center Referral of Patients to Healthcare Facilities
function abnormalities (level 2b).
The acetaminophen nomogram is used by plotting a serum
The acetylcysteine data suffer from the same limits as
acetaminophen concentration at the time after ingestion that it
cohort and case-control studies for decontamination. However,
was drawn. The blood sample should be drawn at 4 hours after
the volume of information available about acetylcysteine and
ingestion or as soon as possible thereafter. For many children,
R. C. DART ET AL.
the ingestions are discovered soon after they occur, raising the
acetaminophen toxicity (alcoholism, isoniazid use, prolonged
issue of when patients should be referred to healthcare facili-
fasting) should be obtained.
ties for further evaluation. If patients are referred immediately,they could arrive more than 3 hours before their blood sample
Patient Age and Intent
is to be drawn. This could allow for the administration of a
All patients in whom suicidal or malicious intent (e.g., child
decontamination method such as ipecac syrup or activated
abuse or neglect) is known or suspected should be referred to
charcoal, but could also produce long waiting times and con-
emergency departments for medical evaluation. Adults with
sume emergency department resources.
definite unintentional ingestion or children less than 6 years ofage in whom neither self-harm nor abuse are suspected can be
Time of Referral
considered for out-of-hospital management.
The data in human volunteers indicate that ipecac-induced
emesis and activated charcoal are both effective in reducing the
Dose and Pattern of Acetaminophen Ingestion
serum concentration of acetaminophen (130). However, sev-
Acetaminophen may be ingested over a short period (acute
eral factors discourage use of these treatments in children.
ingestion) or a longer period (RSTI). Most adult patients with
First, the incidence of serious toxicity from the acute ingestion
single acute ingestions of acetaminophen have attempted self-
of acetaminophen by children is very low (3). Second, the
harm. Patients 6 years of age or older with demonstrated unin-
effectiveness of either ipecac syrup or activated charcoal is
tentional acetaminophen ingestion of at least 10 g or 200 mg/
reduced as time elapses (130). Finally, an effective antidote
kg (whichever is lower) over a period of less than 8 hours war-
(acetylcysteine) is widely available. However, one study (level
rant prompt medical evaluation in an emergency department.
2b) indicated that early activated charcoal administration might
For patients under the age of 6 years, an acute single ingestion
reduce the number of patients that require acetylcysteine treat-
(ingestion period of less than 8 hours) of 200 mg/kg or more
ment (109). The panel determined that if activated charcoal
of acetaminophen warrants evaluation in an emergency
could be administered within 2 hours of a significant acetami-
nophen ingestion, it would be appropriate to do so.
Liver toxicity following acetaminophen RSTI is likely to be
The panel concluded that in the case of a single uninten-
related to both dose and duration of exposure. Therefore, con-
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tional ingestion by a child without suspicious circumstances,
cern for liver injury increases as the dosage increases and as
the child should be referred to arrive in time to have a stat
the duration of ingestion exceeds 24 hours. For patients 6 years
serum acetaminophen concentration determined at 4 hours
of age and older, the panel concluded that referral to an emer-
after ingestion. Thus, the specialist in poison information will
gency department is warranted for those, who ingest at least 10
need to ascertain the travel time for the patient and the poten-
g or 200 mg/kg/day (whichever is less) over a single 24-hour
tial delay at the receiving facility.
period, or at least 6 g or 150 mg/kg/day (whichever is less) per24-hour period for 48 hours or longer. For children less than 6
Type of Healthcare Facility
years of age, the following referral thresholds for repeated
There were no studies found that addressed the issue of the
ingestion were created: 200 mg/kg or more over a period of 8–
type of healthcare facility that would be suitable for managing
24 hours, 150 mg/kg or more per 24-hour period for the pre-
an acetaminophen overdose. The panel concluded that patients
ceding 48 hours, and 100 mg/kg or more per 24-hour period for
should be referred to emergency departments that have the
the preceding 72 hours or longer.
ability to measure serum concentrations of acetaminophen and
Although the data are uncertain, pregnant patients and those
either aspartate aminotransferase (AST) or alanine aminotrans-
with histories of prolonged fasting, chronic ethanol ingestion,
ferase (ALT) in a timely manner.
or chronic isoniazid ingestion should probably be evaluated ifmore than 4 g/day or 100 mg/kg/day (whichever is less) of ace-
taminophen are consumed, particularly if signs consistent with
There were no studies that addressed the frequency or type
acetaminophen hepatotoxicity are present (e.g., repeated vom-
of out-of-hospital follow-up for any type of ingestion.
iting, marked anorexia, jaundice).
Potential Out-of-Hospital Management Techniques
Key Decision Elements
to Prevent or Ameliorate Acetaminophen Toxicity
The panel identified the patient's age, intent, the pattern of
ingestion, as well as the dose and formulation of the acetami-
nophen product ingested as critical information that would be
The consensus panel concluded that activated charcoal
needed in order to make a sound triage decision. In addition,
administration reduced acetaminophen absorption but the
specific information about conditions that might increase
potential risks and overall benefits could not be determined.
OUT-OF-HOSPITAL MANAGEMENT OF ACETAMINOPHEN POISONING
Therefore, the use of decontamination cannot be routinely
form conclusions on several issues due to the lack of informa-
advocated. However, the panel recognized that the use of acti-
tion available. These included the mode of transportation to
vated charcoal should be guided by the individual poison cen-
emergency departments, the effects of circadian rhythm on
ter's assessment of the circumstances, the local policies for
toxicity, the role of patient gender, and the body position for
prehospital care in their service area, and potential benefit-to-
transport. The use of an acetaminophen serum concentration to
risk analysis in their service area. Exceptions should be made
determine the need for acetylcysteine therapy was not
on a case-by-case basis. For example, activated charcoal
addressed by the panel because it is not applied in the out-of-
administration could be appropriate for patients who might
have ingested large doses of acetaminophen and who arelocated several hours from an emergency department.
These recommendations are provided in chronological order
Inhibition of Acetaminophen Metabolism
of likely clinical use. The grade of recommendation is pro-
The panel concluded that the available literature indicates
vided in parentheses.
that cimetidine inhibits the metabolism of acetaminophen.
However, the literature does not convincingly demonstrate that
1. The initial history obtained by the specialist in poison infor-
it improves outcome.
mation should include the patient's age and intent (GradeB), the specific formulation and dose of acetaminophen, the
Detoxification of Acetaminophen Metabolite (NAPQI)
ingestion pattern (single or multiple), duration of ingestion
The panel agreed that acetylcysteine is an effective treat-
(Grade B), and concomitant medications that might have
ment for acetaminophen poisoning, but that there are no pub-
been ingested (Grade D).
lished data regarding the out-of-hospital use of acetylcysteine.
2. Any patient with stated or suspected self-harm or who is the
The panel concluded that acetylcysteine therapy could poten-
recipient of a potentially malicious administration of ace-
tially be initiated in the prehospital environment, especially in
taminophen should be referred to an emergency department
situations in which the emergency department is far away. The
immediately regardless of the amount ingested. This refer-
dietary supplement tablet form of acetylcysteine has not been
ral should be guided by local poison center procedures
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tested as an antidote for acetaminophen toxicity and, therefore,
only the pharmaceutical product should be used.
3. Activated charcoal can be considered if local poison center
policies support its prehospital use, a toxic dose of acetami-nophen has been taken, and fewer than 2 hours have elapsed
Role of Unusual Formulations of Acetaminophen
since the ingestion (Grade A). Gastrointestinal decontamina-
The panel concluded that knowledge of the extended-
tion could be particularly important if acetylcysteine cannot
release nature of a product would not affect the out-of-hospital
be administered within 8 hours of ingestion.
management of a patient. Concomitant ingestion of other sub-stances should be investigated in all patients so that an addi-tional poisoning does not go unrecognized.
Acute, Single, Unintentional Ingestion of Acetaminophen
1. Any patient with signs consistent with acetaminophen poi-
Time of Emergency Department Referral
soning (e.g., repeated vomiting, abdominal tenderness inthe right upper quadrant or mental status changes) should
Patients in whom suicidal, homicidal, or abuse intent is
be referred to an emergency department for evaluation
suspected should be referred to an emergency department
immediately regardless of the dose ingested or the time since
2. Patients less than 6 years of age should be referred to an
ingestion. When the time of ingestion is known accurately
emergency department if the estimated acute ingestion
and suicidal, homicidal, or abuse intent is not involved, the
amount is unknown or is 200 mg/kg or more. Patients can
patient with acetaminophen ingestion alone should be
be observed at home if the dose ingested is less than 200
instructed to arrive at the emergency department in time to
mg/kg (Grade B).
have their stat serum acetaminophen concentration drawn at 4
3. Patients 6 years of age or older should be referred to an
hours after ingestion. Based on the available evidence, a
emergency department if they have ingested at least 10 g or
serum acetaminophen concentration before 4 hours cannot be
200 mg/kg (whichever is lower) or when the amount
ingested is unknown (Grade D).
4. Patients referred to an emergency department should
Other Issues
arrive in time to have a stat serum acetaminophen con-
The panel concluded that poison centers should follow local
centration determined at 4 hours after ingestion or as
procedures for follow-up frequencies. The panel chose not to
soon as possible thereafter. If the time of ingestion is
R. C. DART ET AL.
unknown, the patient should be referred to an emergency
2. Further information regarding the effect of a child's age and
department immediately (Grade D).
the relation to intent is needed.
5. If the initial contact with the poison center occurs more than
3. Further investigation is needed to determine whether any
36 hours after the ingestion and the patient is well, the
subgroup of adult or pediatric patients has increased sus-
patient does not require further evaluation for acetami-
ceptibility to acetaminophen. If this effect exists, it is cru-
nophen toxicity (Grade D).
cial to determine the threshold dose for liver injury in thesespecial populations.
4. Research is needed about out-of-hospital management of
Repeated Supratherapeutic Ingestion of
acetaminophen ingestions in pregnant patients.
5. The feasibility, effectiveness, and safety of the out-of-hospi-
1. Patients under 6 years of age should be referred to an emer-
tal use of acetylcysteine should be investigated (including
gency department immediately if they have ingested:
the use of OTC products).
• 200 mg/kg or more over a single 24-hour period, or
6. The feasibility, effectiveness, and safety of the out-of-hospi-
tal use of activated charcoal for acetaminophen poisoning
• 150 mg/kg or more per 24-hour period for the preced-
should be investigated.
7. Although the phenomenon of RSTI is increasingly recog-
• 100 mg/kg or more per 24-hour period for the preced-
nized, there is little information available concerning it.
ing 72 hours or longer (Grade C).
Research into its pathophysiology and management is
2. Patients 6 years of age or older should be referred to an
emergency department if they have ingested:
• at least 10 g or 200 mg/kg (whichever is less) over a
single 24-hour period, or
Dr. Dart is employed by Denver Health, which provides
• at least 6 g or 150 mg/kg (whichever is less) per 24-
professional services to many pharmaceutical companies,
hour period for the preceding 48 hours or longer.
including McNeil Consumer and Specialty Pharmaceuticals.
There are no other potential conflicts of interest reported by the
Downloaded By: [Alerta - Chile 2005/2006 Consortium] At: 17:16 9 May 2007
3. In patients with conditions purported to increase susceptibil-
expert consensus panel or project staff regarding this guideline.
ity to acetaminophen toxicity (alcoholism, isoniazid use,prolonged fasting), the dose of acetaminophen consideredas RSTI should be greater than 4 g or 100 mg/kg (which-ever is less) per day (Grade D).
Watson WA, Litovitz TL, Klein-Schwartz W, Rodgers GC Jr, Youniss J,
4. Gastrointestinal decontamination is not needed (Grade D).
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117. Rolband GC, Marcuard SP. Cimetidine in the treatment of acetami-
trointestinal decontamination: a state-of-the-art review. Ann Emerg Med
nophen overdose. J Clin Gastroenterol 1991; 13:79–82.
2002; 39:273–286.
APPENDIX 1
Expert Consensus Panel Members
Lisa L. Booze, Pharm.D.
Certified Specialist in Poison InformationMaryland Poison CenterUniversity of Maryland School of PharmacyBaltimore, Maryland
E. Martin Caravati, M.D., M.P.H., F.A.C.M.T., F.A.C.E.P.
Professor of Surgery (Emergency Medicine)University of UtahMedical DirectorUtah Poison CenterSalt Lake City, Utah
Gwenn Christianson, R.N., M.S.N.
Certified Specialist in Poison InformationIndiana Poison CenterIndianapolis, Indiana
Peter A. Chyka, Pharm.D., F.A.A.C.T., D.A.B.A.T.
Professor, Department of PharmacyUniversity of Tennessee Health Science CenterMemphis, Tennessee
R. C. DART ET AL.
Richard C. Dart, M.D., Ph.D.
DirectorRocky Mountain Poison and Drug Center, Denver HealthProfessor of Surgery (Emergency Medicine)University of Colorado Health Sciences CenterDenver, Colorado
Daniel C. Keyes, M.D., M.P.H.
Medical DirectorPine Bluff Chemical Demilitarization FacilityAssociate Professor, Southwestern Toxicology Training ProgramDallas, Texas
Anthony S. Manoguerra, Pharm.D., D.A.B.A.T., F.A.A.C.T.
Professor of Clinical Pharmacy and Associate DeanSchool of Pharmacy and Pharmaceutical SciencesUniversity of California San DiegoFormer Director, California Poison Control System, San Diego DivisionSan Diego, California
Kent R. Olson, M.D., F.A.C.E.P., F.A.A.C.T., F.A.C.M.T.
Medical DirectorCalifornia Poison Control System, San Francisco DivisionClinical Professor of Medicine & PharmacyUniversity of California, San Francisco
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San Francisco, California
Elizabeth J. Scharman, Pharm.D., D.A.B.A.T., B.C.P.S., F.A.A.C.T.
Director, West Virginia Poison CenterProfessor, West Virginia University School of PharmacyDepartment of Clinical PharmacyCharleston, West Virginia
Paul M. Wax, M.D., F.A.C.M.T.
Managing DirectorBanner Poison CenterProfessor of Clinical Emergency MedicineUniversity of Arizona School of MedicinePhoenix, Arizona
Alan D. Woolf, M.D., M.P.H., F.A.C.M.T.
Director, Program in Environmental MedicineChildren's Hospital, BostonAssociate Professor of PediatricsHarvard Medical SchoolBoston, Massachusetts
OUT-OF-HOSPITAL MANAGEMENT OF ACETAMINOPHEN POISONING
APPENDIX 2
Grades of Recommendation and Levels of Evidence
Grade of Recommendation
Level of Evidence
Description of Study Design
Systematic review (with homogeneity) of randomized
Individual randomized clinical trials (with narrow confidence
All or none (all patients died before the drug became available, but
some now survive on it; or when some patients died before thedrug became available, but none now die on it.)
Systematic review (with homogeneity) of cohort studies
Individual cohort study (including low quality randomized
"Outcomes" research
Systemic review (with homogeneity) of case-control studies
Individual case-control study
Case series, single case reports (and poor quality cohort and case
Expert opinion without explicit critical appraisal or based on physiol
or bench research
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APPENDIX 3
Secondary Review Panel Organizations
Ambulatory Pediatric Association
Department of Transportation
American Academy of Breastfeeding Medicine
Emergency Medical Services for Children
American Academy of Emergency Medicine
Emergency Nurses Association
American Academy of Pediatrics
Environmental Protection Agency
American Association for Health Education
European Association of Poisons Control Centres and Clinical
American College of Clinical Pharmacy
American College of Emergency Physicians
Food and Drug Administration
American College of Occupational and Environmental
National Association of Children's Hospitals and Related Insti-
American Public Health Association
National Association of Emergency Medical Services
American Society of Health-System Pharmacists
Association of Maternal and Child Health Programs
National Association of Emergency Medical Technicians
Association of Occupational and Environmental Clinics
National Association of School Nurses
Association of State and Territorial Health Officials
National Association of State Emergency Medical Services
Canadian Association of Poison Control Centres
Centers for Disease Control and Prevention—National Center
National Safe Kids Campaign
for Injury Prevention and Control
Teratology Society
Consumer Federation of America
World Health Organization International Programme on
Consumer Product Safety Commission
R. C. DART ET AL.
APPENDIX 4
Algorithm for Out-of-Hospital Management of Acute Acetaminophen Ingestions
Is self-harm, suicidal, or malicious intent suspected?
YES→ Refer to emergency department.
Does patient have signs of liver failure (e.g., repeatedvomiting,
YES→ Refer to emergency department.
jaundice, right upper abdomen tenderness, mental changes)?
Have more than 36 hours passed since the ingestion?
YES → Toxicity unlikely to occur. No referralor treatment is needed.
Has the patient ingested a potentially toxic dose of acetaminophen
YES→ Refer to emergency department to have stat
(i.e., ≥200 mg/kg for patients <6 yr of age; ≥10 g or ≥200 mg/kg,
serum acetaminophen concentration determined at
whichever is less, for patients ≥6 yr of age)?*
4 hrafter ingestion.
No referral or treatment is needed.
* Activated charcoal should be considered if local poison center policies support its prehospital use, if a toxic dose of ace-
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taminophen has been taken and fewer than 2 hours have elapsed since the ingestion, or if acetylcysteine cannot be initiated within8 hours after the ingestion.
APPENDIX 5
Algorithm for Out-of-Hospital Management of Repeated Supratherapeutic Acetaminophen Ingestions (RSTI)
Is self-harm, suicidal, or malicious intent suspected?
YES → Refer to emergency department.
Has the patient ingested a potentially toxic dose of acetaminophen?
YES → Refer to emergency department.
For patients <6 yr of age:
≥200 mg/kg over 8–24 hours
≥150 mg/kg/day for 2 days
≥100 mg/kg/day for 3 days or longer
For patients ≥6 yr of age:*
≥10 g or 200 mg/kg (whichever is less) over a single 24-hour period
≥6 g or 150 mg/kg (whichever is less) per 24-hour period for
48 hours or longer
No referral or treatment is needed.
*A referral dose of 4 g/day or 100 mg/kg/day (whichever is less) should be considered for patients with suspected risk fac-tors(e.g., alcoholism, isoniazid therapy, prolonged fasting).
Source: http://cituc.saluduc.cl/medios/CITUC/pdf/acetaminophen_15685042594bd59e64937c9.pdf
UNIVERSIDAD DE LA REPÚBLICAFACULTAD DE ENFERMERÍA Factores que inciden en el consumo de psicofármacos en el personal de enfermería de una institución médica del interior del Uruguay Br. Alvarez, Catalina Br. Lapido, Soledad Br. Lorduguin, Florencia Br. Mantuani, Flavia M Prof. Agda. Esp. Lic. Enf. Garay, Margarita Prof. Agdo. Mg. Lic. Enf. Díaz, Álvaro
ORIGINAL INVESTIGATION Updating the Beers Criteria for PotentiallyInappropriate Medication Use in Older Adults Results of a US Consensus Panel of Experts Donna M. Fick, PhD, RN; James W. Cooper, PhD, RPh; William E. Wade, PharmD, FASHP, FCCP;Jennifer L. Waller, PhD; J. Ross Maclean, MD; Mark H. Beers, MD Background: Medication toxic effects and drug-